The present invention concerns conveyor systems having a first array of supply conveyors and a second array of receiving conveyors. More particularly, the invention concerns a transfer car that travels between the array of supply and receiving conveyors to transfer items from one array to another.
In modern article handling facilities, such as factories, warehouses and distribution centers, it is a frequent practice to have an array of supply conveyors and a second separate array of receiving conveyors. The supply conveyors can receive packages or products from a manufacturing and/or assembly line, or from a product sorting system. The receiving conveyors can accept the products at a number of different conveyor sections corresponding to different outgoing locations. For instance, in a warehousing scenario, the supply conveyors can accept a variety of products from a sorting network. The receiving conveyors can correspond to particular destinations to which the sorted products will be sent. Likewise, in a factory setting, newly manufactured product can be accumulated on several supply conveyors and then subsequently transferred to destination specific receiving conveyors.
In warehouse or distribution systems involving a limited number of products or a minimal number of outgoing destinations, certain automated conveyor systems are acceptable that automatically switch products from one supply conveyor section to another outgoing conveyor section. However, where a number of products are being sorted and distributed, and/or a number of outgoing locations are being serviced, the number and frequencies of transfers between incoming and outgoing conveyor sections is so large that relying upon direct mechanical transfer between input and output is not feasible. In these instances, it is a frequent practice to utilize one array of supply conveyors and a separate array of receiving conveyors that are separated by an aisleway. A transfer car then traverses the aisleway between the two conveyor arrays. Products can be transferred to a supply conveyor section to the transfer car, which then carries the products to one of the receiving conveyor sections for subsequent transport.
In a typical application, the transfer cars are automatic, meaning that they can be programmed to follow a predetermined sequence between supply conveyor sections and receiving conveyor sections. In some cases, the automatic transfer cars are equipped with bar code readers or scanners that scan labels on the products to determine where a particular product is intended to go. In a production facility, the automated transfer car can be programmed to extract newly manufactured product from machine specific supply conveyor sections and deliver the product to destination specific receiving conveyor sections.
One such approach is illustrated in FIG. 1. An array of supply conveyor sections 10 are oriented across an aisleway A from an array of receiving conveyor sections 11. Although only one conveyor in each section is depicted, it is understood that in a typical set up a plurality of such conveyor sections would be included. Moreover, the conveyor sections may be dispersed at various locations throughout the building or warehouse. Regardless of the configuration, however, the aisleway A is maintained between the supply and receiving conveyor arrays.
In this typical installation, a transfer car 15 is provided that traverses the aisleway A between the conveyor arrays. The transfer car in one application includes a transfer conveyor assembly 16 mounted on the moveable car. As shown in FIG. 1, the transfer conveyor assembly is aligned parallel with the conveying direction C of the two conveyor arrays. Thus, in a typical operation, a product P is conveyed by supply conveyor section 10 toward the transfer car 15. The transfer conveyor assembly 16 on the transfer car 15 can be powered or simply freewheeling to accept the product P. As shown in the figure, the receiving conveyor section 11 can be directly across from the supply conveyor section 10, so that the product P can be transferred directly to the receiving conveyor section 11. However, typically the transfer car 15 would travel along the aisleway A to another receiving conveyor section. At this point, the package is discharged from the transfer car transfer conveyor assembly 16 onto the receiving conveyor section 11. In some cases, the transfer car 15 is manually operated, meaning that a human operator stands at one end of the transfer car and directs its operation. In other typical installations, the transfer car 15 travels automatically along the aisleway A. Specifically, a track T is used to guide the path of the transfer car 15. In some instances, the track T is formed in the floor of the building, in the form of a railroad track or a continuous slot. Appropriate features on the transfer car 15 allow the car to follow the track T. In other cases, the track T can be electronic, with appropriate sensing devices on the transfer car 15 to guide the car between the opposing conveyor sections 10 and 11.
Automatic transfer cars have vastly simplified the process of transferring products P from one point to another in a factory, warehouse or distribution center. However, as with any powered or driven vehicle, safety concerns continuously arise. Various industrial safety regulations require specific safety features on automated equipment of this type. For instance, flashing lights and sound alerts may be mounted on the transfer car as an apparent warning to workers that may be passing through the aisleway A. More sophisticated, and consequently much more expensive, pathway sensors determine whether an object or a person is in the aisleway, at which point the transfer car 15 is directed to stop.
Of course, as with many safety features, they are not completely foolproof, meaning that injuries by use of the transfer car 15 can result in ways not accounted for by the safety features. One specific problem that arises frequently with respect to automated transfer cars arises at the shear point S between the transfer car and the conveyor sections. Specifically, the shear point S constitutes the narrow gap that exists between the sides of the transfer car and the ends of the opposing conveyor sections. This gap must, by necessity, be relatively small so that the products P can be easily conveyed from conveyor section to transfer car and back to conveyor section without hanging up. In addition, space concerns may necessitate a tight clearance between the sides of the transfer car and the ends of the conveyor sections. In a typical installation, the shear point S is only about 1.5 inches wide.
One problem that arises is that workers standing adjacent one end of the transfer car may not be aware of an oncoming transfer car and can have a body part trapped or pinched at the shear point S as the transfer car passes. Many safety features are unable to prevent this type of occurrence. Photoelectric pathway sensors may not sense the presence of a person at the side of a transfer car or approaching from the side of the transfer car. A lack of attention may make the visible and audible warnings ineffective.
While the automated transfer car is a great benefit to product distribution, it still carries an inherent safety risk. Thus far, no known automated transfer cars adequately account for this risk. The danger can be reduced if the shear point S is widened at the opposite sides of the transfer car 15. However, this physical modification to the transfer car can make it impossible to transfer product P to and from the transfer car. While this approach may work for large products, it is not acceptable for smaller products that may fall into the enlarged space between transfer car and conveyor section. The same problem is inherent with sheet products that may not rest entirely flat on the conveyor sections during transfer.
There is therefore a need for a transfer car that retains the capability of the prior art systems while avoiding the perils associated with the usage of automated vehicles of this type. In other words, there is a need for a transfer car that eliminates the dangerous shear point S while maintaining the product transfer surface of the transfer car as close to the ends of the conveyor sections as possible.